This invention relates generally to the recycling of waste materials; more specifically, it relates to an apparatus having particular utility in the cleaning of used plastic containers, packaging and the like. One use for such an apparatus is to clean the polystyrene material recovered from food containers that are commonly used by so-called fast food restaurants to dispense food products such as hamburgers, breakfast sandwiches, coffee, etc. Another use is to clean the polyethylene recovered from milk cartons, oil jugs, antifreeze containers, soap and detergent bottles, etc.
It is well known that many communities are rapidly approaching a crisis stage in dealing with solid waste products. This is because the most common technique of disposing of such products has been to bury them, along with other trash, in "solid" landfills. As old landfills have approached their capacity to receive fresh trash, sites for locating new landfills have been complicated by the difficulty of finding suitable land and an increased concern for environmental factors, including the possible contamination of ground water by chemicals that sometimes leach out of such landfills. To perhaps reduce the burden on traditional landfills, many persons have turned their attention to minimizing the solid waste that must be accommodated as a result of having to deal with plastic containers and packaging, especially those that have not been formulated so as to be biodegradable. It is no secret that if packaging waste could be minimized, then landfills could be used much longer before they are full.
It is also well known in the plastics industry that flawed packages, cups and containers for food and beverages can frequently be recycled by grinding or chopping the flawed products and using the resultant particulate material as a portion of the feed stock that is supplied to an extruder or the like. Examples of teachings on this subject can be found in the following U.S. Pat. No. 3,000,055 to Schlicksupp entitled "Grinding, Mixing and Feeding Apparatus for Plastic Molding Machines," No. 4,091,967 to Kinoshita entitled "Device for Dealing with the Scraps of Foamed Thermoplastic Synthetic Resins," and No. 4,254,068 to Otsuka entitled "Method and Apparatus for Regenerating Foamed Plastics." Of course, the recycling of scrap and rejects in a factory is done under circumstances that may be described as relatively clean, because scrap and rejects have not yet been soiled by the solids or liquids that such containers and packages are designed to hold. Therefore, the principles that apply to the traditional reuse of scrap and rejects in a factory cannot be transferred--without alteration--to recycling centers where contaminated packages and containers are accumulated.
When it is contemplated that one might wish to recycle used food and beverage packages (such as those used to serve hamburgers, coffee and similar food products at fast-food restaurants), a significant problem arises, namely, how to deal with the now-soiled plastic packages. By use of the word "soiled," reference is being made to the residue that remains on a package after all large food particles have been removed. Such residue may include what is left of food that was supplied by the original food preparer, as well as other items such as garnishes that may have been supplied by a purchaser. Additionally, there may be items such as chewing gum that were never an integral part of someone's meal but which frequently show up in discarded trash. Of course, chewing gum, like mustard and the like, does not readily shake free of a package when an attempt is made to empty the package of any remaining food. Therefore, it must be contemplated that discarded food containers may be soiled (or contaminated) with one or more of the following items: catsup, mayonnaise, mustard, relish, grease, butter, margarine, jelly, vinegar, salad dressing, taco sauce, refried beans, gravy, tartar sauce, dried egg, soy sauce, chicken fat, syrup, chocolate, ice cream--and the juices that are produced by tomatoes, hot peppers, pickles, and onions, etc. It follows, then, that used food and beverage containers must somehow be cleaned of such contaminants before the plastic in such containers could ever be seriously considered for recycling. Furthermore, such containers must be cleaned within hours of the time that the containers (along with other trash) are received in a recycling center. (It should be no surprise that authorities who are responsible for public health will not tolerate the accumulation of trash that might attract rodents, flies, cockroaches, etc.) It is an object of this invention to provide a cleaning apparatus that is serviceable as a necessary part of a recycling apparatus--said cleaning apparatus being useful to clean the packaging material and render it fit for subsequent processing.
Recognition of the need for an effective cleaning apparatus is, of course, not a recent event. At least as early as 1977, a U.S. patent application was filed by Paul G. Marsh entitled "Recovery of Plastic From Municipal Waste"; this application matured into U.S. Pat. No. 4,160,772 in 1979. In the Marsh patent, it is acknowledged that the product realized from practice of the '772 invention may require further cleaning before it is used in a recycling process. But the only cleaning solution offered by Marsh was a conventional shaking screen, which is reportedly well known in the preliminary cleaning of rags in the preparation of paper-making stock. Of course, the kinds of contaminants that are likely to be on food containers are probably going to be much harder to remove than any accumulation of dust, etc. It follows, therefore, that there has remained a need for a cleaning apparatus that will render suitable for recycling those plastics that were described by Marsh, but which are contaminated to a degree that presumably was never considered by Marsh. An object of this invention is to satisfy that need.
Another object is to provide a cleaning apparatus that can operate without any moving parts, but which provides substantial turbulence within a cleaning liquid--to foster the kind of agitation and movement that is conducive to cleaning all surfaces of a package fragment.
Still another object is to provide a cleaning apparatus whose size and shape can be readily altered, as required, to fit the particular volume of material that is to be handled.
One more object is to teach a technique for reclaiming the plastic in used food containers, for the purpose of reusing the raw materials that were originally used to make the containers, as well as reducing the need for waste disposal space for solid materials.
A further object is to teach an apparatus that is usable for cleaning a variety of different plastic materials with only small alterations, such as harvesting plastic fragments from the bottom of a water tank instead of the top of the tank (when the fragments are heavier than water), etc.,
These and other objects will be apparent from a reading of the specification and the claims appended thereto, and with reference to the drawings attached hereto.